The ability for a molecule to move into and out of a cell can have a significant effect on the intracellular concentration of the molecule. For example, if the molecule is a nutrient, then slowing the movement of the molecule into the cell would inhibit growth (Herbert, D & H L Kornberg, Biochem. J. 156(2), 477-480, 1976). If the molecule is a toxin, then slowing the movement of the molecule out of the cell would inhibit growth. If the molecule is a substrate in a reaction, then slowing the movement of the molecule into the cell would slow down the rate of the reaction. If the molecule is an intermediate in a series of reactions, then slowing the movement of the molecule out of the cell and allowing it to accumulate inside the cell could lead to feedback inhibition (Kikuchi et al., FEMS Microbiology Letters 173:211-215, 1999; Ogawa-Miyata et al., Biosci. Biotechnol. Biochem. 65:1149-1154, 2001).
Previous studies of the production of amino acids, such as lysine, and amino acid-derived products, such as cadaverine, focus on the overexpression or attenuation of genes involved in cellular metabolism. These modifications increase fluxes that lead to the production of the desired product, and decrease fluxes that lead to the production of side products or other metabolites not necessary for the formation of the desired product. However, additional methods of increasing the production of amino acids and their derived products are needed.